Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Income tax provision	$ 38,608		$ 30,783	$ 98,473	$ 82,663
Effective income tax rates	37.10%		38.10%	37.40%	37.80%
Actual income tax rates	37.30%		37.20%	36.00%	36.70%
Unrecognized income tax benefits	$ 1,900			$ 1,900		$ 4,000
Unrecognized income tax benefits, if recognized, that would favorably affect the effective income tax rate	700			700		2,200
Accrued interest expense related to unrecognized income tax benefits	200			200		$ 500
Interest income related to unrecognized income tax benefits			$ 100	$ 300	$ 100
Interest expense related to unrecognized income tax benefits	$ 100
Unrecognized tax benefits, decrease resulting from settlements with taxing authorities		$ 3,300